The present invention addresses several problems in known food service apparatuses and processes.
A representative current procedure for supplying food at institutions or the like requires lengthy set-up time and, thus, increases scheduling problems. A current airline heating procedure at least includes the steps of placing frozen meals on sheet pans, adding an insulated cover to the meals, placing the sheet pans on racks in a rethermalization cart, tempering the food to about 40.degree. F. (for example, thawing overnight under refrigeration), activating a timer to cause preheating of the oven, removing the insulated cover, covering the food with foil, perforating the foil, heating the tempered food in about forty minutes, testing for 180.degree. temperature, removing the foil, possibly physically transferring the cart to an assembly line, removing the hot food from the cart, assembling the hot food dishes onto trays containing cold food, stacking the trays and applying an insulated cover.
The known prior art includes one or two removable elements, such as a tray or a shelf, in a system. The known prior art does not, however, address modular systems in which the container of food, a food positioning template, a heat transferring element, and a multi-function drawer are all removable from a chamber without the use of tools for ease of cleaning and simplicity of repairs. Also, several known systems include exposed electrical elements on the chamber which could lead to exposed hot prongs if the chamber circuit was turned on and the mating drawer, shelf, tray or the like was not inserted in the chamber.
The known prior art also does not appear to teach the advantages of a multi-function drawer or shelf in a chamber which not only can support heat transferring elements, but can also provide power to heat transfer elements and direct heat downward towards a subjacent container of food. In addition, the known prior art does not appear to teach a one-element mechanical and electrical removable engagement of this multi-function drawer with the chamber which is secure during moving of a portable housing. With respect to the removable heat transfer element, the prior art does not appear to teach the advantage of using a removable heat transfer element to supply power to an adjacent heat transfer element to extend the number of removable heat transfer elements which could be disposed on one removable drawer or shelf. Further, the prior art does not appear to identify the advantages of having removable positioning templates of differing shapes to increase the flexibility of the heating chamber to handle different shaped containers of food to be heated.
Ovens which primarily provide conduction-only heating, are not advantageous for cooking frozen foods, because the top may not cook before the bottom scorches. With portable convection-only ovens, the heating is slow and these ovens have a tendency to dry out the food. Thus, many prior art devices rely on a separate rethermalization step to thaw the frozen food to the tempered (40.degree.-50.degree. F.) range before heating by conduction. U.S. Pat. No. 3,608,627 to Shevlin, however, teaches going directly from a frozen state to a heated state. There are, though, problems with the structure of Shevlin. Shevlin still includes the complexity of a combined refrigerating/heating chamber. It also has a complicated covered casserole structure and possibly heats the frozen food too rapidly. In Shevlin, a sheet or foil and a cover must be added to a container either before loading or while the container is in the chamber, and the same sheet or foil and cover must be removed after heating. In addition, heating frozen food in under thirty minutes as taught by Shevlin, likely requires using a high temperature heater element and, thus, introduces the likelihood of scorching the food.
With respect to insulation, many rethermalization systems merely use an insulated cover over a container to try to prevent heat loss to the inside of a refrigerated chamber and to try to prevent cool air from coming into the food in the covered container. With respect to the inside of the chamber in relation to the surrounding environment, known prior art devices rely primarily on filling cavities with commercial insulation materials. Known prior art devices do not appear to address designing the actual structure of the housing and its associated elements to further aid in keeping the inside of the chamber at the desired temperature. Also, known prior art devices doe not appear to teach ways to minimize the amount of ambient air which contacts food in a container, when a portion of the housing or chamber is opened for allowing access to other containers of the same chamber.
Finally, known prior art devices do not appear to address waterproofing the electrical connectors on the inside of a chamber, waterproofing the electrical connectors on a removable drawer or shelf and waterproofing the electrical connectors on removable heat transfer elements so that the removable elements and the chamber can be pressure water cleanable.
The food preparation apparatus and process of the present invention was developed to overcome the structural and functional limitations of the prior art systems and methods discussed above.